Machines, such as haul trucks and wheel loaders, each include a powertrain that provides torque to wheels of the machines. The powertrain generally consists of a combustion engine, a powershift transmission connected to an output of the engine, and an output transfer group (a.k.a., a drop box) that selectively delivers power from the transmission to front and rear axles of the machine.
An exemplary output transfer group is disclosed in U.S. Pat. No. 8,365,637 that issued to Herold et al. on Feb. 5, 2013 (the '637 patent). Specifically, the '637 patent discloses an output transfer group having a housing with a single input port and three output couplers. Two of the output couplers are used to drive axles of a mobile machine, and one output coupler is used to power a draw-works assembly mounted to the machine. An output shaft of a transmission is received within the input port, and a front axle coupler is located below the input port. The draw works coupler and a rear axle coupler extend from an opposite side of the housing. A hydraulic circuit having a dedicated filter is provided for connection of the couplers to a source of lubricant. The output transfer group also includes a gear train that selectively connects the output shaft of the transmission to each of the different couplers by way of a coupling mechanism. The gear train includes an input gear connected to the transmission output shaft by way of the input port, an output gear connectable to the front and rear axle couplers, and a transfer gear that extends between the input and output gears.
Although the output transfer group of the '637 patent may be suitable for some applications, it may be less than optimal, For example, the output transfer group, having its own hydraulic circuit, may be large, complex, and expensive.
The disclosed hydraulic circuit is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.